Nonmetallic sheathed conductor



Aug. 5, 1941. c. w. ABBOTT NONMETALLIC SHEATHED CONDUCTOR 2 Sheets-Sheetl Filed Aug. 3, 1940 lv'ENToR CMAQ/ Es W A515077' BY www Aug. 5, 1941.c. w. ABBoTT NONMETALLIC SHEATHED `CONDUCTOR Filed Aug. 3, 1940 2Sheets-Sheet 2 @gw mm L31.

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R V.. m .m EA lo Wmm i Q MEW Patented Aug. 5, 1941 AUNITI-:D STATESPATENT OFFICE.

This invention relates to electrical conductor construction andparticularly to insulated electrical conductors intended primarily forinstallation in buildings to form the circuit or circuits usually forlighting, power, and like uses.

One of the objects of this invention is to provide an insulatedconductor or so-called cab1e" construction that will be inexpensive tomanufacture, of'compact construction, and eicient, safe and reliableaction and well adapted to meet the widely varying conditions orrequirements met with in the building Wiring eld, illustratively inframe and like residence structures, farm buildings, and the like.Another object is to provide an insulated conductor or cableconstruction utilizing rubber or rubber compounds `and other insulatingmaterials in such a way as toA make it possible to employ smallerquantities of rubber or rubber compound while maintaining adequate andelectrically safe insulation appropriate to the various conditions underwhich the conductor must in practice stand up. Another object is toprovide a conductor construction of the above-mentioned nature in whichvinsulating Walls of rubber or rubber compound, or the like, may beemployed but in a thickness or thicknesses materially less than hasheretofore been possible and to provide for such insulating walls oflesser thickness dependable and lasting me# chanicai protection againstinjury or deformation in the manufacture, handling, or use, of theinsulated conductor construction.

Another 'object is to provide improved mechanical protection that willbe easy to manufacture, inexpensive in construction, and eiiicient inaction, for the rubber or like insulating wall or sheath of anelectrical conductor. Another object is to provide mechanical protectionof the the cable construction is subjected in actual use tection of theabove-mentioned character for the rubber or like insulating wall. orlayer takes part, with the rubber wall or layer, in achievingeiiiciently and inexpensively the desired overall dielectric strength orinsulation desired for the conductor or conductors of the constructionor cable.

Another object is to provide a cable or insulated conductor constructionthat will have improved operating characteristics with respect tovarious conditions met with in installations of conductors of this type.For example, where moisture conditions are present, it has happened,

in prior constructions, that elements employed in building up the sheathfor the conductor or conductors act as wicks and thus wick the moistureback into the cable structure from the open ends of the latter as inoutlets, causing rotting and often giving rise to fungus growths whichin turn take part in both so-called dry" and Wet" rot. Sometimes acidicconditions are met with, frequentlxly in farm installations, as in cowbarns, and acid fumes or acid-.carrying moisture have been knowndestructively to attack non-metallic sheathed cable constructions asheretofore employed; for example, a wicking action like that justmentioned in connection with moisture carries the acidity into theinternal cable structure with impairment of insulation e characteristicsand of mechanical protection. Also, various saturants employed on bothinternal and external sheathing elements have been known to be attackedor dissolved or their usefulness greatly impaired by such conditions ofacidity. Another object is to provide a cable construction that will vdependably and in an inexpensive way overcome after installation,material or harmful injuryI insulated conductor construction in whichpro# Another object is to provide an insulated conductor structure orcable ci the above-mentioned character that will dependably function ininstallations of the character mentioned above without requiringmetallic sheathing, or the like, and to provide a non-metallic sheathedcable or insu-lated conductor construction that will be inexpensive,strong, ccmpact, electrically safe and reliable and mechanically andphysically resistant in an efficient and lasting manner to the varionsand varying hazards to which such conductor, in such instaliations,might be subjected.

Another object is to provide an insulated com ductor construction of theabove-mentioned character that has dependable resistance to stretch andthereby to protect the individual wires or conductors against elongationwith accompanying diminution in cross-section, when the cableconstruction is subjected to stress. Another object is to provide acable construction that will be simple, easy and quick for theelectrician to prepare, at its end or ends, for electrical connection,and more particularly to provide for ease and speed of removal of thesheathing or sheathing elements to expose the individual wires orconductors. Another object is to provide for long lasting and dependabledistinguishing or identification of polarities of the several conductorswhere the cable is made up as a plural conductor cable. Another objectis in general and in detail toprovide an improved insulated conductor orcable construction of the above-mentioned general kind.

Another object is to provide a dependable and eicient method ofmanufacturing insulated conductor constructions of the above-mentionedcharacter and one that will lend itself to economic, speedy andefficient carrying out in practice and capable of high rates ofproduction. Another object is to provide a simple and practical methodof applying a sheathing element in plastic form to a conductorstructure. Another object is in general and in detail to provide animproved method of sheathing a conductor or conductors.

Other objects will be in part obvious or in part pointed outhereinafter.

The invention accordingly consists in the features of construction,combinations of elements, arrangements of parts, and in the severalsteps and relation and order of each of the same to one or more of theothers, all as will be illustratively described herein, and the scope ofthe application of which will be indicated in the following claims.

In the accompanying drawings in which are shown by way of illustrationseveral of the various possible embodiments of the mechanical featuresof my invention,

Figure l is a diagrammatic representation of a sequence of apparatusillustrative of several of the earlier steps employed inmy method;

Figure 2 is a similar diagrammatic representation of a sequence ofapparatus for carrying out certain subsequent steps of my method;

Figure 3 is a central longitudinal vertical sectional view on anenlarged scale of part of the apparatus of Figure 2 showing its relationto the conductor being operated upon;

Figure 4 is a diagrammatical plan View of an applicator means as seenalong the line 4 4 of Figure 2;

Figure 5 is a plan View of an insulated conductor or cable constructionwith parts progressively removed or broken away or shown in section toshow the various elements and their structural interrelationships, andwith other parts removed or broken away to show a possible or preferredaction of stripping certain of the sheathing elements;

Figure 6 is a similar view showing another form of construction, and vFigure 7 is a View like that of Figure l iilustrating another form ofconductor construction.

Similar reference characters refer to similar parts throughout theseveral views of the draw ings.

In order to make for a readier understanding of the various features ofmy invention, let it be assumed that the cable or insulated conductorconstruction is to be installed as part of a building or householdwiring system, usually of volts, for lighting and analogous or relatedpurposes; while my invention may be embodied in single-conductor form,it may be and preferably is embodied in plural-conductor form and inFigures 5 6 and '7 of the drawings the several forms there shown,embody, by way of illustration, two conductors I0.and II which may beassumed, when installed, to represent or to be part of the lighting orpower circuit, and hence being usually subjected t0 a normal operatingpotential difference or Voltage of 110. These conductors are usuallysolid or single strand. To the extent that non-metallic sheathedconductor or cable has heretofore been employed in practice, theconductor or conductors thereof have embodied, usually as an initiallayer of insulation, a layer of rubber or like'compound, vulcanized inthe form of a jacket surrounding the conductor, but it has long beenconsidered unsafe, in such prior practices, to employ a wall thicknessfor the rubber jacket less than a certain limiting value, due to variousand numerous factors involving elements of construction, manufacture,installation, conditions of use, and the like. In the preferred form orforms of my invention, and in so far as certain features thereof areconcerned, I preferably employ a rubber jacket, preferably extruded ontothe conductor and then vulcanized in any usual or suitable way, as bythe known process or apparatus of continuous extrusion andvulcanization, but I am enabled very materially and with safety toreduce the thickness of the wall of such a rubber jacket and thus alsoto reduce the amount of rubber needed.

Thus, referring to Figure 5, and since certain -of the elements appliedto the two conductors I0 and I I are preferably the same and applied inthe same manner, it Will suffice to describe these aspects of myinvention only with respect to conductor I0 onto which is extruded arubber jacket I2 and vulcanized; jacket I2 is preferably of lesser wallthickness than has heretofore been possible, for example, a reduction inWall thickness on the order of 40%.

A Among the reasons why, in the processing or manufacture of cable orconductor of this general type according to prior constructions andmethods, reduction of rubber Wall thickness was not carried out, is inthe fact that the insulating materials superimposed upon the rubber,usually immediately afterivulcanizatlon, have been of a nature and havebeen applied'under such conditions of pressure or tension that harmfuldeformation of the rubber, usually still in a somewhat soft condition,would result. Also, as is usually the case, the conductor is of solidmetal so that any bending or flexing thereof during various stages ofprocessing would tend also to effect deformation or distortion of therubber Jacket, and in various ways, such as in a di rection outwardlythrough the rubber or like compound of the jacket, due to the directinternal action thereon by the conductor itself.

Having applied the jacket I2 of rubber, or like compound, for example inthe manner above ndicated, as above noted also, I apply thereto acoating, indicated at I3, of a suitable material or compound, preferablycapable of being applied in liquid or semi-liquid form, but which, uponbcoming set, is dry, exible, and preferably also somewhat elastic, andhas preferably also good or suitable adhesion to the rubber jacket I2.The material, compound, or composition, employed to form the coating orlayer I3, may vary widely and preferably and illustratively' I employ alacquer whose ingredients are suited vor selected, in a manner known inthe art, according to the manner or "method of application thereof tothe element l2 and to the ultimate characteristics, such as thoseabove-mentioned, desired. Thus, in the numerous compositions of variousingredients are y,available for this purpose; such compositions arereferred to, in certain of the claims hereof as being of the lacquerclass. I preferably and illustratively employ a lacquer having for itsbase a. cellulose derivative, preferably cellulose nitrate, and havingincluded therein a suitable solvent or solvents and a suitableplasticizer or plasticizers. The application of the coating material maybe carried on in any suitable or known way and when the solvent or othervolatile constituents (in the case of lacquers) are evaporated or drivenoff, the material becomes set with the desired degree of hardness andthickness of coating as well as sufficient flexibility and elasticitythereof to be somewhat yieldable and stretchable, thus to avoidcracking, chipping or cra-zing. The resultant coating I3, which may beof a thickness on the order of several thousandths of an inch, is also,in preferred form, quite smooth and slippery, its exposed surface beingof low coeiiicient of friction in coaction with other material which Imay use superimposed vupon or about the layer Y or coating I3.

Preferably, the material of the coating I3 is of the type, such as theabove-mentioned lacquer,

that sets in response to the application thereto 10 iielcis of lacquersand liquefiable synthetics alone of Aheat or Whose rate of setting isincreased in response to the application of heat; in such way, I preferto apply the coating material to the rubber-jacketed conductor while thelatter with its jacket retains or has a heat content derived from thestep of vulcanization.

Thus, as diagrammatically shown in Figure l, I prefer to use acontinuous vulcanizer I4 through which the rubber-jacketed conductorIII-I2 is drawn at a suitable speed, a speed which may be on the orderoi several hundred feet per minute; the vulcanizer I4 comprises apipe-like chamber of suitable length charged or supplied with steam atsuitable pressure and temperature so that the conductor emergestherefrom with its rubber jacket I2 practically or completelyvulcanized;

any suitable form of continuous vulcanizer may be employed and, as isusual in practice, it is preferably associated directly with anextrusion head or machine which extrudes the rubber jacket onto theWire.

Emerging from thevulcanizer I4, the still hot jacketed conductor, thetemperature or heat content of which may at this stage be altered,ifdesired, by a suitable heat exchanger (not shown) passes through anapplicator I5 in the form oi a suitable device or chamber containing thecoating material, such as lacquer, supplied thereto as from a tank IEand provided with suitable means, such as a rubber element or elements,at its righthand or outlet end to regulate or nx the thickness of thecoating with which the rubber-jacketed conductor emerges therefrom. Theheat content of the jacket I2 or oi the wire I0 or of both heattreats orsets the thus applied coating I3, insuring also a good bond between itand the rubber to which, it will be noted, the coating material isapplied while the rubber surface is still virgin and in eiect open-poredor in a condition analogous to porosity. g

The coating is strong, relatively tough, and affords mechanicalprotection and reinforcement to the rubber jacket I 2. Moreover, andpreferably, I include in the compound of which the coating I3 is formed,such as lacquer, suitable coloring materialafpreferably in the form ofpigments and, where a plural conductor cable is to be constructed, asthe two-conductor cable of Figure 5, the pigment employed in the coatingon rubber-jacketed conductor III is different from the pigment employedin that of rubber-jacketed conductor I I, thus to distinguish theseveral conductors in 'the cable.v selected according to existing colorcodes and thus, in a two-conductor structure like Figure, the coloringor pigmentation of the one coating may be gray and of the other may beblack. In a structure like that of Figure 5 and for reasons later setforth, I prefer next to apply over the coating I3 a layer or coating ofa suitable wax-like material; in Figure 5 that coating is' indicated atIl and it is preferably applied as a a step following the step ofapplyingV and setting the coating I3.

Thus, I may provide an applicator chamber I8 throughwhich the conductor,structure passes and which contains a suitable wax-like material inheated and hence substantially` liquid form, thus coating the conductorelement, any suitable means being provided, if desired, to determine, asby a yieldable wipe, or the-like, the thickness of the layer picked upby the conductor element as it passes through the bath in the applicatorI8.

Since, in the preferred process, where the conductor continues to moveat the substantial speed at which it is extruded and vulcanized, theconductor element emerges from the coating applicator I5 in a stillheated condition even though some of its heat content has beendissipated in setting the coating I3, and. hence I prefer appropriatelyto regulate or interrelate the characteristics of the wax-like materialand the temperature or heat content and speed of' the conductor element.Thus, for exfu may regulate the heat content of the r nf element by a.suitable heat exchanger i, shown) interposed between the applicators i5and I8 and thus suit it to the characteristic of melting point andviscosity of the material in applicator I8, it being noted that whenfthe conductor emerges from applicator I8, the wax-like material shouldset relatively quickly rather than be kept in such a state of fluidityby the heat content of the conductor element as to cause unevendistribution of the coating, particularly where the conductor elementmoves in a general horizontal direction.

Or, as in the preferred step, I may achieve such a suitableinterrelation of factors by utilizing a wax or like compound that has amelting point suihcie'ntly high relative to the temperature or heatcontent of the moving conductor element that setting at the desired rateand even distribution or thickness of coating are achieved. Also andpreferably I prefer to use a wax compound of appro; siate body; forexample, I may employ a Wax loaded with zinc stearate, having a meltingpoint on the order of 16o" F., somewhat higher than the temperature ofthe jacketed conductor element as it enters the applicator I8. Theloaded wax has sufri- These pigments may bev and hence uniformity ofthickness during and f after setting results.

The wax compound-in applicator I8 is prefer' ably circulatedtherethrough in heated and liquid condition by any suitable means, suchas a pump 20, connected in series by suitable piping with'the applicatorI8 anda tank 2| which is provided with any suitable heating meansdiagrammaticallyindicated at 22. f

If desired also setting of the wax coating, which may have a thicknesson the order of 0.015 inch or cooling of the coated conductor elementmay be effected by a suitable heat exchange device 23.

Subsequent steps are effected at a lower rate of speed of movement ofthe conductor element and hence it is preferred now to reel up theconductor element -I2-I3-I`I and in this connection the cooling by heatexchanger 23 may be used to facilitate immediate reeling up.

'From such reels, the element is run off and during continuous movementthereof, in the pref ferred form of my method, I perform a succession ofoperations diagrammatically indicated in Figure 2, and of which thefirst comprises Winding about the element and hence onto thelast-applied coating, in the above instance being the wax coating I1, aband or tape-like member 24. The latter is preferably of paper and ofsuitable thickness and width, illustratively a thickness of 0.0025 inchand a width of 1A" and it is wound helically preferably with a smalloverlap.

A ny suitable apparatus.diagrammatically indicated at 25 may be employedfor thus Wrapping the member 24 as the conductor element continues tomove in a direction toward the right as viewed in Figure 2; the speed ofsuch movement may be on the order of 60 feet per minute. Leaving thewrapping machine 25, the conductor structure enters a suitable machineor apparatus Awhich applies to the structure and onto the last-appliedlayer of material, in the illustrative embodiment being the paper wrap24, a continuous helix of a cord-like element 2'I wound at a pitch toleave a suitable spacing between successive turns somewhat analogous toa form of screw thread. Member 2l may be substantially round incross-section and is preferably made of twisted paper, being thus a formof so-called paper cord. The pitch of winding may be such,illustratively, as to give a spacing on the order of Ps" from center tocenter of successive turns, thus forming a helical rib lengthwise of thestructure and forming a helical space.

The rib 2T! may be made of relatively tough or strong construction andis preferably wound with sufficient tension or tautness as to cause eachturn to resist shifting thereof relative to the underlying supportingcore structure. The tenacious and relatively tough coating I3.of lacquersupplemented by. the paper or layer 24 forms a dependable foundationlfor this helical rib 2l and the coating i3 in coaction with the covering2d also protect the rubber jacket l2 against detrimental distortion orcompression under the winding tension of the rib member 2l.

Continuing its movement toward the right, the structure, now with thehelical rib 2l' about it, passes through an applicator apparatus,generally indicated by the reference character 23. and which, where thematerial to be next applied to the conductor structurt is athermoplastic having preferred characteristics as later described,preferably takes the form shown in Figures 2, 3 and 4.

Thus, the apparatus 28 may comprise a tank 30 of suitable capacity anddepth to contain the plastic material and provided with suitable meansfor insuring its application to the conductor structure. The latter mayenter through a suitable bushing, or the like, 3| in one end wall of thetank 30 and pass through a suitable device 32 suitably relatedl to theopposite end wall. The device 32 preferably comprises an internallytapered tube-like element having a land or portion 32a at its exit orright-hand end (Figure 3) that is of uniform inside diameter somewhatless than the outside diameter of the helical rib 21; for example, ifthe outside diameter of the rib 21, in a structure utilizing No. 14 B &S gage wire for the conductors I0 and II is 0.18.7 inch, the insidediameter of the straight portion 32 is about 0.175 inch to 0.180 inch.With this preferred restricted exit throat in element 32, the conductorstructure drawn therethrough is subjected to some degree of compression,particularly the turns of the helical rib 2l, and' other actions takeplace as later described.

To the left of the straight restricted portion 32, the internal diameterof the tube-like appli.

cator member'32 increases, preferably gradually, thus to form by itstapered internal walls guides for the plastic material, as is laterdescribed, and also guides to enter the turns of the helix 21 neatly andsnug y into the restricted throat portion 32,

vMember 32 is mounted in any suitable manner to the end wall of the tank30 and preferably detachably; thus, it may be externally threaded at itsleft-hand end and threaded into a collar or bushing 33 in the end Wallof the tank.

As the structure is drawn through the tank 3U, the plastic compound ispicked up or applied to the rib structure and the latter with thecompound enters the member 32 where the plastic material is indicated at34. If desired, suitable means may be employed to insure the applicationof the material 34 to the moving conductor structure so that, forexample, the application of the material does not have to depend toomuch upon the depth or amount of material in the tank. For

example, Imayemploysuitablerotarymeans, such as two spaced disk members35, 33 (Figure 4) xed to a shaft'l driven by any suitable means, such asa motor 38, at a suitable speed and positioned relative to the bottom ofthe tank and the line or axis of movement of the conductor structure,somewhat as is indicated in Figure 2, so that at least portions of therotary members 35 and 36 are always submerged and as they rotate theypick up and wipe onto the axially moving conductor structure suitablequantities of the plastic material 34.

The material 34 is preferably a thermo-plastic that is preferablyquick-setting and, at temperatures usually encountered in the storage ori11- stallation or subsequent use of the finished cable construction, isnon-migrating, relatively tough, yieldable or resilient; suchtemperatures might range from around 30 F. to 180 F. It preferably hasother characteristics later pointed out.

For example, this composition or compound may comprise asphalt, bitumen,coal tar pitch, petroleum pitch, vegetable stearine pitch, animalstearine pitch, or like hydrocarbonaceous materials, preferably insuitable combination or combinations with suitable fillers, preferablyinert mineral fillers, such as limestone, siliceous materials, likemica, fillers like talc, slate flour, asbestos, diatomaceous earths, andthe like, Nylon or glass bcrflockings, etc.

An illustrative mixture or compound comprises by weight '15% of oxidizedpetroleum asphalt, 10% of slate our, 10% of Muscovite (flake) mica, andof Biotite mica. By way of further illustration another compound may.comprise by weight 50% of oxidized petroleum asphalt, 30% of inactiveasphalt, 10% of Muscovite mica, and of fine divided asbestos. Anotherillustrative compound may comprise by Weight 70% of oxidized petroleumasphalt, 20% of slate flour and 10% of shredded mica.

Such amixture or compound is placed in the tank 30 (Figures 2 and 4)where it is preferably maintained in a suitable plastic or appropriatelyworkable state preferably by heat, the tank 30 having associated with itany suitable heating means diagrammatically indicated at 40 andpreferably also the tube-like member 32 is heated by any suitable means,such as a jacket or electric heating unit, or the like, diagrammaticallyindicated at 4I. The temperature at which the material is maintainedpreferably is related to the composition and hence characteristics ofthe thermo-plastic such as the reaction of the material of the helicalrib 21 and the material of the wrap 24 and of other elements as is laterpointed out. Thus, utilizing one of the above-mentioned illustrativecornpositions for the material 34,its temperature When in the tank Illand while operated upon by the tubular member 32 is on the order of 300F., it being noted that a slightly higher temperature is utilized wherethe percentage of filler is higher..

At such a temperature, the mass is suitably workable to take part in theactions of application about to be described, particularly at the speedof movement of the conductor structure or core, and moreover, does notdetrimentally affect the materials, illustratively paper, of the helicalrib 21 and the underlying wrap'24, nor does it affect,

, as by over-vulcanization, the rubber jacket I2.

The mass of material in the applicator tank 30,

though relatively dense or thick .and having subf stantial body, hasportions of it transferred steadily onto the moving conductor or corestructure, illustratively by the rotating applicator members and 36,where the conductor or core structure is not submerged in the plasticmass itself. This transfer or application may and frequently does takeplace with some non-uniformity in that over-excess of the plasticmaterial may be thus transferred. But the core structure with theplastic material wiped or smeared or otherwise transferred onto itentersthe tapered interior of the device 32 (Figure 3), the tapered orprogressively restricted walls thereof compaeting or forcing thematerial inwardly toward the axis of the conductor structure,particularly in the tapered region just to the left of the straight orland portion 32n above-described. As the material is thus pressedinwardly against and about thc structure, the relatively rigid andnon-migrating rib structure 21 vano to move the compressed materialalong with thc conductor structure andto resist displacement ormigration thereof relative to the moving conductor structure, at leastso much of the surrounding mass as occupies the continuous helical actslike a continuous material 34 and'to related factors,

paper, takes place in a space formed by the helical rib 21. In effect,the helical rib, after the progressively restricted space within lthemember 32 packs the material against the base of this helical space,specifically against the wrap 24, forces or pulls the material alongwith the movement of the conductor-core structure and thus insures thatthat helical space is completely filled up.

As the parts enter and move through the straight or land portion 32a(Figure 3), a combined compressing, smoothing and wiping action takesplace, preferably extent to somewhat compress or diminish the outsidediameter of the helical rib 21. In the course of this action thematerial is compacted against the wrap 24, into any interstices that mayexist in the rib structure 21 itself or between it and the wrap 24 andalso against or onto or into the now somewhat flattened external face ofthe helical rib, emerging from the member 32 as a smooth cylindricalelement substantially free from undulations and in appearance being ofthe color of the plastic material 34 itself, usually black, with thehelical rib 21 hardly or not at all discernible due principally to theimpregnation or covering (in an outer layer) of its material by and withthe plastic itself. The above described actions are preferablyfacilitated by maintaining the temperature at a suitable level as by theheater 4I above described. The plastic material, filling the helicalspace, appears as a helically distributed band or ribbon of subtantialthickness, and as such an entity is indicated in Figure 5 by thereference character 42.

While the `iust described physical actions are taking place, otheractions, in this preferred method and form of conductor structure, alsotake place. Thus, the material of the helical rib 21, preferably oftwisted paper, becomes impregnated by the plastic material and a similarimpregnation of the wrap 24, also preferably of direction from itsexternal surface toward its internal surface. The above-describedmagnitude of temperature, it

' might be noted, does not detrimentally affect the paper of thejust-mentioned elements.

The heat content of the plastic material, howover, and as soon as it isbrought into thermal contact with the wrap 24, acts upon the Wax of thecoating I1 which is heated suiliciently to impregnate the wrap 24 in adirection from its interior face or surface toward the outer face, andthus I may achieve impregnation of the wrap 24. Though thereby the-waxof the coating I1 may be somewhat diminished, there is enough wax lefteither in the coating or at the inner surface of the wrap 24 tofunction, in a sense like a lubricant, to insure ease of relativemovement or slippage between the rubber-,jacketed structure or core andthe wrap 24 and the parts that are external of the latter, though itwill be understood that even in the complete absence of wax or of a waxysurfacing or impregnation of the wrap 24, the coating I3, preferably andillustratively of lacquer,I as above described, preferably has a smoothand slippery external surface which by itself facilitates such relativeslippage or movetreat the material ment, as in bending or curving thevconductor structure either in subsequent stages of manufacture orthereafter. Also, it will be understood that if desired I may initiallyimpregnato or suitable wax or by the use of a suitable saturant; in suchcase, I may or may not, as desired, -utilize a wax coating like coatingI1. The structure also, as above noted, to an of the wrap 24 as by useof a' emerging from the applicator apparatus 28 (Figure 2) next hasapplied to it a covering preierably in the form of a band or tape-likeelement 43 preferably of paper, preferably employing any suitable formof tape wrapping machine,- as is diagrammatically indicated at 44 inAFigure 2. This paper tape 43 is preferably very thin and may be', forexample, made of a rope-sulphite paper preferablyin a width commensuratewith the width of the wrap 24 and applied preferably with a slightoverlap, directly over the structure which, as above noted, and asindicated in Figures 2 and 3, presents an external substantiallycylindrical surface of plastic material. Onto the latter the wrap 43 isapplied and preferably before the mass has materially cooled oil andhence is still at the temperature at which it'leaves the applicatorapparatus 28.

It will be understood, however, that I may, in any suitable manner, asby a heat exchanger (not shown) suit the temperature of the conductor orcore structure, now embodying the thermo-plastic, to the desiredconditions or circumstances of application of the wrap 43.

For example, I prefer to have the mass 42 (Figures 2 and 5) at atemperature such that there is adhesion or uniting between the tape 43and the element 42 and preferably also imprega nation of the former bythe latter, thus bringing about an action similar to that abovedescribed in connection with the tape or wrap 24,; where the temperatureof the compound or material in the tank 30 is on the order of 300 F.,the temperature, by Way of illustration, at the time of the applicationof the paper tape 43 may be somewhat less and hence on the order of 280F.

Next I prefer to apply a coating of wax, indicated in Figure 5 at 45,and this application may be made in any suitable Way as the conductor orcore construction continues to move along. Thus, the wax-like materialemployed may be similar to that used in` making the coating I1 and asimilar form of apparatus may lbe employed, comprising, for example, anapplicater chamber 46 (Figure 2) suitably supplied with the wax materialat suitable temperature, as, for example, by'means of a pump 41 seriallyconnected through suitable piping with the applicator 46 and with a tank'48, suitable heating means diagrammatically indicated at 50 beingemployed to keep the wax at a suitable temperature and a suitable degreeof fluidity.

The wax compound may be of any suitable composition and may be loaded orotherwise compounded so that it will have suitable body so that, inrelation to the heat content or temperature of the core or conductorstructure onto which the wax coating is thus applied, the wax coatingdoes not appreciably migrate or flow, thus to achieve uniformity ofthickness during and aftersetting of the coating. But preferably coating45 is relatively thin and in such case, such factors as bodycharacteristic may be given less consideration.

Also, it will be understood that if desired I may initially impregnateor treat the material of the wrap or tape 43 as by use of a suitable waxor other suitable saturant; in such case I may or may not, as desiredand depending upon cir-y cumstances, utilize a separate wax coating 45,

' it being noted that in such case the lheat content of the corestructure, principally of the thermoplastic element 42, may take part ineffecting a softening or melting of the saturant, where a.)

impregnated tape 43 with its saturant to its new helical condition andpreferably also to effect a binding or adhesion between the material orelement 42 and the band member 43.

Usually and preferably, the conductor structure is now reeled up and inthis connection a suitable heat exchanger (not shown) if desired may beused to reduce the heat content of the structure, andfrom such reels theconductor element may now be further processed. Onto the core thusformed I now apply an outer covering element 5l (Figure 5) which is.preferably braided on, as by using cotton braid, but preferably,because of factors later mentioned, after first applying a suitablesheet material like paper, as indicated at 49, and Where the cable is tocontain more than one conductor, illustratively the two conductors I0,of Figure 5, two such cores are encased side by side first in the sheetmaterial 49 and then in the sleeve or tube-like braid formation 5|, theseveral cores being together run through a suitable machine'to applyfirst the sheet material 49 and then the braided covering 5| thereover.The element or material 49 may be applied in the form of a helix or wrapwith a suitable overlap or it may extend longitudinally with its twolongitudinal edge portions overlapped; crinkled kraft paper ispreferably employed.

Where two such cores are thus assembled, there extend lengthwise of themtwo valleys formed by the side by side relationship of the two cores.Due to such features of construction and steps of operation as thoseabove described, the outside diameters of these core structures arematerially less than in structures heretofore employed, being each, inthe illustrative embodiment, on the order of 0.180 inch in diameter, andthese valleys are relatively small. Into preferably only one of them,such as the upper one as seen in the plan view of Figure 5, I run a cordelement 52 which has substantial tensile strength for its smallcross-section and which preferably also is nonporous or non-cellular anddevoid of a wicking action; a suitable material for this paper is a cordor yarn made of woven or twisted synthetic fiber, preferably ofsynthetic or artificial silk,

wax-like material is used, to reaccommodate the -such as the kind knownand available on the market by the trade name Nylon Even in the smallcross-section appropriate to substantially fill in this small valley,Nylon yarn has a tensile strength on the order of pounds. It is run intothe valley along with the two conductor cores, entering the machine thatapplies the paper sheath 49. In the other valley I prefer to employ aless expensive material and here a small-cross-sectioned yarn or cord orpaper or jute 53, suitably impregnated or saturated, may be employed.

The braided covering 5| having been completed, I now subject it tosuitable treatment in any suitable way, as by impregnation with suitablecompounds or materials to give it the desired moisture-proof,fire-resistant, mold-resistant, and like characteristics. Thus, I mayrun the structure successively through saturating baths, for example,first througha tank containing the saturant that gives the braidcovering 5| moistureproof qualities, then through a tank to give itflame-resistant and moisture-proof qualities, the sheath 49 acting as abarrier, dam or baille to block penetration of the braid-impregnatingcompound beyond the thickness of the braid itself or to block migrationof the compound to or into other parts of the structure.

able or resilient at ordinary temperatures met Lastly, I prefer toapply, after drying or setting of the just-mentioned saturants, a final1 coating, indicated at 54 in Figure 5, of a material preferably of thegeneral characteristics and composition like that of which the coatingi3 abovedescribed may be made, excepting that, where 1 employ a pigmentor coloring element-as an ingredient, I prefer to use aluminum powder asa pigment. Thus, the coating 54 may be in the form of a pigment-carryinglacquer, preferably compounded to be quick-drying so as to facilitateair drying, though it will be understood that any other suitable meansmay be employed to effect relatively quick setting of the coating. Sucha coating though applied in a relatively thin layer is resistant to andsubstantially impervious to acid-bearing fumes, such as those earliermentioned above, it films over and thus covers or seals, with arelatively tough stretchable or resilien t skin interstices, and thelike, that frequently occur in the braid structure and its saturants, itis resistant to or unaffected by high temperatures liable to be met within practice and thus counteracts migration of fillers or saturants inthe underlying braid, it being noted that frequently such llers orsaturants have relatively low melting points or become flowable atrelatively low temperatures. Thus, a clean non-tacky longlasting easilyhandled structure results. Such a. coating is impervious to moisture, isstrongly resistant to weather, and the like, and adds protection againstthe effects of the sun. Also, the materials of which it is made orcompounded lend themselves easily' and inexpensively to coloring as bypigments, and thus I am enabled to give the final cable structure a neatand attractive appearance in contrast to the crude appearance ofstructures heretofore employed, a factor-which has limited its scope ofpractical application. Also, such a iinal coating forms a good base forordinary types of paints, and thus the cable structure may be painted,for example, when in' stalled.

',Ihe construction I am enabled to embody in materially smallercross-section than the crosssection of cable conductors heretoforeemployed; for example, in the two-conductor structure of Figure 5,utilizing two No. 14 wires, the dimen-l sion along the major axis may beon the order of 1/8 less than the dimension along the minor axis .on theorder of 114 less than the corre- Ali) with in installation and ldoesnot migrate or ilow, even at the higher temperatures met with. Beingpresent in the form of la helix in the helical space formed by the ribstructure 21 and each turn thereof being Well backed up by therelatively tough or rigid adjacent turns of the rib structure 21, thestructure offers dependable mechanical resistance to mechanical injury,such as penetration by nails, or the like, any tendency to displace theelement 42 or part of it( see Figure 5) being strongly resistant byV therib structure 21 and other elements that take part in coniining thematerial. The rib structure 21 itself offers strong resistance tomechanical injury and is well adapted to veering off instruments likeanail, an action in which the compound of the material 42 may take partor which it may assert of itself.

The pliancy or elasticity of the material of element 42 facilitatesbending or curving of the structure and in its preferred form itspenetration into and adhesion to its directly associated elements, suchas the helical rib 21 insure against opening up or the creation ofcracks or fissures at the longest radius of curvature when the-structure is bent and the rib structure 21 insures maintenance ofconcentricity or roundness of the built-up structure. Preferably, also,

sponding dimensions in prior commercial types oi l construction, Thus,also, substantial economies in shipping weight, less bulk and greaterfacility in handling and greater range of usefulness, such as in passagethrough smaller holes or entry into more restricted spaces, in course ofinstallation, result. Also, less crowding of conductors in outlet boxes,and the like, may be had.

The construction is also less expensive and the method lends itself tocommercial operation on a quantity production scale. For example, theapplication of the material 34 in Figures 2, 3 and 4 is simply anddependably carried on; the helical rib structure 21 in coaction withother elements insures proper application of the material and makespossible the employment of inexpensive compounds and compounds of lowtemperature characteristics. Thus, also, considerable loading of thecompound, as by such fillers or loaders, preferably inorganic, as thosementioned above, with attendant advantages, may take place evengthoughthe compound may as a result be relatively stiif.

In the cable structure the element 42 is yield-v ease of bending orcurving is contributed to by relative ease of sliding or slippagebetween the interior face of the wrap 24 and the element underneath it,such as the coating i3 which is pref-- erably slippery, asabove-mentioned, or such as the wax coating I1; in such bending orcurving, also, relative ease of slippage between the inside face of theelement 49 and the elements contacting therewith, such as the paper wrap43 or the wax coating 45, is preferably present.

Also, I achieve safety and facility of manipulation or handling ininstallation. The tensile strength of the element 52, even though ofsmall cross-section, resists tensile stresses to which the cablestructure may be subjected, as by pullingf and thus resists elongationof the copper conductors and accompanying reduction in crosssectionthereof. Also, the tensile strength of element 52 makes it possible forit to function as a dependable rip cord for unsheathing the outerelements of the structure, as by causing the cord 52 to tear, cut or ripthe coverings 49 and 5l, as when the ends of the cable structure are tobe exposed in turn to be "stripped to expose the wires themselves.

In this latter connection, due to characteristics of the material ofelement 42 and coactions thereof with other elements, some of which arementioned above. the relatively strong and tough` helical element 21acts as a stripping element, `for its extreme end need onlybe graspedand pulled in the general direction of the axis of the conductor,resulting in a sort of unwinding action but accompanied by the removal,with the element 21 and as a unit therewith, of the inner wrap 24, theouter wrap 43, and the compound element 42, the adhesion of the latterto the former and to the helical element 21 causing them all to beremoved cleanly, and at substantially the same speed or quickness withwhich the helical rib 21 itself could be disassembled by a `pullgenerally in the above-mentioned direction.` Thus, element 21 partssheet elements 24 and 43 either at their overlaps or by tearing andparts the turns of helical mass 42; the coating i3, .when and whereemployed, becomes exposed and where it carries a coloring or pigmentpolarity or like identification of the individual conductor is at oncepresent; the rubber jacket I2 is easily stripped off in known manner andthus the bared conductors are available for making electricalconnection.

In installation high protection against moisture, fungi or mold,acid-bearing fumes or vapors, and like effects is achieved. Wickingaction is dependably resisted and the small dimensions and compactnessof construction with resultant greater ease and dependability of fillingthe valleys guard against the presence of hollow spaces along whichinfiltration of moisture or acid-bearing air or gases might otherwisetake place. Wicking action by wayof such elements as members 24, 21 and43, as to moisture, or the like, is well guarded against, even thoughthese elements may be made of an organic material like paper, by thecoverage or impregnation thereof, or both, by the compound or materialof element 42, While the same or similar effects guard against movementof moisture, or the like, in a radial direction inwardly through theseelements, the material of element 42 itself being impervious to moistureand', as above indicated, comprising also preferably inorganic elementsand being inert. In effect, the structure also adequately andpermanently encloses or seals the rubber or like material of the jacketI2 of the conductor or conductors against passage or infiltration ofmoisture, fumes, fungi, mold, or other deleterious elements or effects.If desired, also, rodent repellants in the form of suitable saturants orlingredients may be incorporated in the elements 24, 21 and 43 orcompounded with the material of element 42.

The above-described construction and method lend themselves tomodification or variation. Thus, for example, and returning to Figure 6,the material of element 42 above described may be interrelated withother elements, such as an underlying helical element 56 of fiber-likestrands of glass, preferably of a diameter or degree of fineness justlarge or heavy enough to permit them to become interwoven, orintermingled, or

matted or felted together in a manner analogous to glass wool,preferably with a binding material, such as a phenolic condensationproduct. Element 56 occupies part of the depth-of the helical spacebetween the helical rib element 21 and may be applied in any suitablemanner, preferably by means of a separate carrier element, such aspaper, which may comprise a paper wrap 24a to which the glass fiberelement 56 adheres or is bound, as by the above-mentioned bindingmaterial. The rest of the depth of the helical space may be filled witha material like the material 34, above-described, and of which theabovementioned element 42 is made, being shown in Figure 6 at 42a.Depending upon its composition, the application of element 42u proceeds'preferably in the manner above described, as in connection with Figures2, 3 and 4, and preferably under conditions such as cause it to bepressed into and impregnate such tape or paper elements with which itcontacts and to become also adhered to the glass fiber element 56; or,to illustrate another form which the material 34 may take for making upa helical element of the general shape of element 42 of Figure 5 or formaking up an element like element 42a of Figure 6 in association with amaterial like fiber glass, it may comprise suitably small particles ofsuitable material bound together and preferably also bound to the partsor surfaces of the conductor core structure with which it is inengagement, an illustrative material comprising verrniculites insuitably divided form, usually granular or flake-like, theabovementioned binding being achieved by a suitable binder which maytake the form of a phenolic condensation product, any suitablenon-.conductive plastic cement, such as rubber cements, latex, or thelike. In its application, as by an apparatus like that indicated inFigure 3, the helical rib element 21 preferably takes part in insuring,in coaction with the interior faces of member 32, the application of themass of vermiculite particles with their binder, much in the same manneras was described above in connection with Figure 3. Otherwise, theprocedure and the lpreferred coacting elements of the construction areas those described in connection with Figure 5, it being noted that themass of boundtogether vermiculite particles has pliancy and flexibility,individual particles stretching or expanding or contracting.

With a construction like that of Figure 6, stripping off, as by pullingupon the end of the helical element 21 at the end of the conductorstructure may be effected with the facility described above inconnection with Figure 5. strippi-ng and also certain of the earlierabovementioned advantages of 'my'invention may be achieved with astructure like that shown in Figure 7 where the helical space formed bythe helical rib element 21 is occupied entirely bya material like thefiber glass element 5B above-.described, the binding element of which,or a suitable similar binder, preferably binding elements 24, 56, 43together and to the helical rib element 21. Pulling the latter at itsend thus strips off a composite but unitary helix made up of theseelements, thus quickly exposing the underlying element or elements.

.Where a mass of particles like verrniculite is employed, the materialof the particles is preferably inorganic and substantially inertchemically; where fiber-like material, like the glass fibers of element56, is employed, the material thereof preferably has similarcharacteristics, and, moreover, both materials, being inorganic, do notencourage the formation or growth of mold. Fiber-like elements ofmineral base, such as Nylon, may also be employed. In applying suchmaterials, the application proceeds preferably with the accompaniment ofheat which may be applied in any suitable manner to drive off I noisturethat may be related to the materials as, for

example, in interstices between fiber-like elements or 'betweenparticles and also where, as is preferred, an inorganic heat-responsivebinderis employed. Thus, or in any other suitable manner, heat treatmentmay bring about such interactions as impregnation of the tape-likeelements 24 and 43 and the rib structure 21 with wax-like material, suchas the material of coating I1, or the saturant (where one is employed)in such elements as elements 24, 21 and 43, or a binding together, asmentioned above in connection with Figure 7, to facilitate stripping offof the various elements as a unitary helix, as is preferred.

Recurring to Figure l, subsequent to the step of applying the coatingI3, as by the apparatus I5-I6, and just before completion of setting ofthe applied coating, particularly where it takes the form of a lacquer,I prefer to apply thereto a material comprising small particles orflakes, indicated at |38, preferably mica of suitable and preferablyvery small mesh; any suitable means (not shown) such as a head orchamber con- Such facility of a helical form, means binding said helicalsneatntaining the material and through which the coated conductor coreis drawn, may be used to make the application. The particles partiallyembed themselves inthe outermost portions of the coating, it being notedthat in the preferred manner of applying a heat-responsive coatingvnamely, to utilize the heat content of the rubber handling becomenecessary at `that stage of the preferred form of process.

.In the completed conductor structure, as in Figures 5, 6v and '7, theseparticles I3 toughen the coating and when made of mica contribute afactor of lubrication to still more facilitate ease of relative movementbetween the coated internal core structure and the parts overlying it,as when bending or curving the conductor structure. Such an externalapplication of such particles does not detrimentally aiect colorelements or pigmentation. of the coating material.

Thus, it will be seen that there has been provided in this invention aconductor construction and a method of processing the same in which thevarious objects hereinbefore noted together with many thoroughlylpractical advantages, are successfully achieved. It will be seen that Iam enabled to combat effectively the various elements which in priorpractice have been found to have detrimental effects upon materials asheretofore employed; thus, for example, entry of moisture, or the like,into the structure is counteracted in a dependable, inexpensive, compactand mechanically and electrically vefiicient structure, utilizingtherein'preferably inorganic non-hygroscopic elements and reliablyrendering non-hygroscopic such other elements as are for various otherreasons of organic material, such as paper. It will be seen that theconstruction is well adapted to meet the varying conditions of hardpractical use. a

As many possible embodiments may be made of the mechanical features ofthe above invention and as the art herein described might be ing meansand said helical rib together and upon -both sides of the latter to formtherewith a substantially continuous insulating and mechanicallyprotective jacket of substantial thickness, and removable coveringsheath means thereover, the tensile strength of said rib element beingsuiilcient, when said covering sheath means is removed and uponsubsequent pulling the end of said helical rib element in the generaldirection of the axis, to break the bond between said helical sheathingmeans and said helical rib element on that side of the latter opposed tothe direction of the coating, and thus faclliy latter given a helicalform, with a varied in various parts, all without departing from thescope of the invention, it .is to be understoodA that all matterhereinabove set forth, or shown in the accompanying drawings is to beinterpreted as illustrative and not ina limiting sense.

I claim:

1. An insulating conductor construction of the character describedcomprising a conductor core structure having thereabout a helical tapeelement, a rib element of substantial thickness -and ytensile strengthand extending helically at substantial pitch` about said core structureand tape and whose side walls are denned by the sides vof adjacent turnsof said rib element, pliant v stantial thickness and element, therebyprovidingl a'. helical space therei about of substantial radialdimension and whose bottom comprises portions of said tape `element ofpull on the rib element and throughout as ,sheathing means as correspondto the axial length of said core structure -to be bared, said bindingmeans having a strength normally to hold said helical sheathing meansand helical rib element bound together on both flexing of the entireconductor construction and also bound together, as said rib element ispulled, on that side of the rib element in the direction of pulling ofthe latter, thereby to remove said helical sheathing means substantiallyas a unit with said rib element and to expose said core structure.

2. A conductor construction as claimed in claim `1 in which said helicalsheathing means comprises a. mass of material that is pliant at theusual range of temperature of operation or installation of the conductorand which at higher temperatures has suilicient mobility to impregnateimpregnatable fibrous elements, said tape element and said rib elementbeing made of impregnatable fibrous material, said binding meanscomprising portions of said mass flowed under heat into said tape andrib elements.

3. A conductor construction Aas claimed in claim l in which said helicalsheathing means comprises a mass of intermingled fibers ofnon-conductive material in said helical vspace and by the binder bindingsaid fibers together, whereby upon pulling said rib element thehelically shaped mass of boundtogether bers is removed turn by turn withsaid `rib element.

4. A conductor construction as claimed in claim 1 in which said helicalsheathing means comprises at least two superimposed helical layerscharacter described, in combination a conductor core structurecomprising a conductor andv a. rubber Jacket, said core structure havingthereabout a non-conductive sheet-like material overlying said rubberjacket, a rib element of subof a non-conductive material resistant tocompression extending helically about said sheet-like material andforming an open winding to provide a helical space, the turns of saidrib element having a tightness of winding appropriate to resist shiftrelative to one another and said sheet-like material coacting to'protect the rubber of said jacket against the tightness of winding ofsaid rib element, means comprising atough pliantnon-,flowable-insulatlng mass compacted into said helical space, anonconductive sheet material overlying said insulatsides of the latterduring ,l

' axis of the structure, said casing backing up and reinforcing saidlast-mentioned sheet material in confining said pliant non-flowablehelical mass whereby the insulating elements about the rubber jacketprotect the latter mechanically against crushing, deformation, and thelike and displacement, as by an implement, oi said mass in said helicalspace is resisted by its inherent characteristics and by its coniiningelements including said helical rib element.

b'. An insulated conductor as claimed in claim in which said masscomprises a material that is pliant and non-flowable at operating andinstallation ranges of temperatures and that is relatively flowable andhas adhesive qualities a't higher temperatures, said helical mass, saidrib element, and said two sheet materials being bound together by thematerial of the mass itself under heat treatment at said highertemperatures.

7. An insulated conductor as .claimed in claim 5 in which the materialof said mass in said helical space is non-hygroscopic, and attemperatures higher than operatingl or installation temperatures hascharacteristics'of mobility and adhesiveness, said helical least saidrst-mentioned sheet material being substantially impregnated by materialof said mass under initial conditions of suiiicient temperature to eiectimpregnation and adhesion.

8. An insulated conductor as claimed in claim 5 in which there isinterposed between the rubber jacket and said first-mentioned sheetmaterial a tough, resilient stretchable coating of a material of thelacquer class, said coating being bound to the rubber jacket andreinforcing the latter mechanically against the winding pressure of saidhelical rib element.

9. An insulated conductor as claimed in claim 5 in which there isinterposed between the rubber jacket and the first-mentioned sheetmaterial a means acting to provide for relative ease of slippage, asduring bending, between the jacket and said first-mentioned sheetmaterial, thereby, during bending, to permit relative sellaccommodation,according to the radius oi' bending, between said conductor and rubberjacket as one unit and said mst-mentioned sheet material with said ribelement, insulating mass and overlying sheet material as another unit.

10. An insulated conductor as claimed in claim 5 in which there isinterposed between the rubber jacket and the first-mentioned sheetmaterial a coating of a material of the lacquer class, said coatingbeing bound to said rubber jacket and being pliant and stretchabletherewith .to provide relative ease of slippage between the jacket andsaid rst-mentioned sheet material,

A thereby, during bending, to permit relative selfaccommodation,according to the radius of bending, between said conductor and rubberjacket as one unit and said first-mentioned sheet material with said ribelement, insulating mass and overlying sheet material as another unit.

1`l. An insulated conductor as claimed in claim 5 in which there isinterposed between rib element and aty the rubber jacket and therst-mentoiled sheet material a coating of a material of the lacquerclass, and having at its surface or projecting therefrom andsubstantially uniformly distributed small particles or iiakes ofnon-conductive materialI thereby, during bending, to permit relativeself-accommodation, according to the radius of bending, between saidconductor and rubber jacket as one unit and said firstmentioned sheetmaterial with said rib element. insulating mass and overlying sheetvmaterial as I another unit.

least one valley having 12. An insulated plural-conductor constructionof the character described comprising an outer tearable sheath or jacketencasing a plurality of conductor structures each comprising a conductorhaving an insulating and protecting sheathing means that comprises a ribelement of substantial thickness and of a material resistant tocompression and extending helically and forming an open winding toprovide a helical space of a depth commensurate with the thickness ofthe rib element and insulating and protective means accommodated in saidhelical space, the rib elements of said conductor structures and theirrespective insulating and protective means of said helical spacescoacting to resist diminution of the spacing between the axes of saidconductor structures within said outer sheath and the valleys formedalong said plurality of conductor structures being lled with suitablemeans including a cord element in at substantial tensile strength,whereby it functions as a rip cord to rlp lengthwise said outer sheathto expose the c plurality of conductor structures, said rib eletiveinsulating and protective means, the conductors may be by the coloringor pigment means distinguished from one another.

14. In a method of sheathing and insulating an" electrical conductor,the steps which comprise forming a conductor core structure by applyinga rubber jacket to a conductor and by applying over the rubber jacket anon-metallic material to give the rubber of the jacket ease oi slippage,applying a sheet-like material next to said last-mentioned material andabout said core structure for'the reception thereon of subsequentlyapplied insulating and sheathing elements and to carry the latter forrelative ease of lslippage with respect to said rubber jacket, Windinghelically about said sheet material a rib element of substantialthickness and of a masheet material a non-metallic casing to back up2,251,262 and reinforce said last-mentioned sheet material tocompression and at a long lay to provide a v helical space betweenadjacent turns and at sufficient tension so that the turns thereofresist displacement, compacting into said helical space and in heatedcondition a mass of insulating material that is pliant and non-ilowableat operating or installation ranges of temperature and that isrelatively ilowable and has adhesive qualities when in heated condition,thereby to flow and compact said material into said helical space and tocause it to bind said sheet material and said rib element together,applying a sheet material thereover and while said mass in said helicalspace is still in heated condition, thereby to cause said second sheetmaterial to become bound to said helical mass, and building thereover anon-metallic casing. y

16. In a method of sheathing andinsulating an electrical conductor, thesteps which comprise forming a conductor core structure by applying arubber jacket to a conductor, applying an impregnable sheet materialexternally of said core structure, winding thereover a rib element ofsubstantial thickness and of a non-metallic material resistant tocompression and at a long lay to provide a helical space betweenadjacent turns, compacting into said helical space and in heatedcondition a mass of insulating material that is pliant and non-ilowableat operating or installation temperatures and that is relativelyilowable when in heated condition'beyond said temperature ranges tothereby impregnate and bind said sheet material, applying thereover animpregnable sheet material under temperature conditions high enough tocause impregnation thereof by the material of said mass, and buildingthereover a non-metallic casing.

17. In a method of sheathing and insulating an electrical conductor, thesteps which comprise forming a conductor core structure by applying arubber jacket to a conductor, applying and binding to the rubber jacketa relatively thin tcugh'stretchable coating to reinforce the rubber ofthe jacket, winding helically thereabout a/rib element o! substantialthickness and of a nonmetallic material resistant to compression at along lay to provide a helical space between adjacent turns and atsullicienttension so that the turns thereof resist displacement,compacting into the helical space. a pliant non-flowable insulatingmass, and applying thereover non-metallic sheathing means to form anon-metallic casing to coact with said helical rib element in confiningsaid insulating mass in said helical space.

1s. 1n a method of sheathing and insulating a conductor the steps whichcomprise vulcanizing a rubber jacket about a conductor, applying to therubber jacket while still retaining heat from the step of vulcanizing aheat-responsive coating material that is set by the heat content of saidjacket, winding thereabout a rib element helically at a long lay toprovide a. helical space between adjacent turns, compacting into saidhelical space and in heated condition a protective insulating mediumthatis pliant at operating or installation temperatures and that isrelatively nowable when in heated condition at temperatures insufficientto over-vulcanize the rubber of said jacket, and applying thereovernon-metallic coniining and insulating casing means.

19. An insulated conductor construction of the character described, incombination, a conductor core structure comprising .a conductor and arubber jacket, said core structure being enveloped by a built-up7insulating and protective sheathing structure that comprises a ribelement of substantial thickness and of a material resistant tocompression extending helically about said core structure at a long layto provide a helical space betweenA adjacent turns, with a mass ofinsulating material that is tough, pliant andnon-ilowable at operatingand installation ranges of temperature and that has characteristics ofmobility and adhesiveness at higher temperatures compacted into saidhelical space, there being interposed between said core structure andsaid insulating material a layer of non-conductive meterial adhesivelybound to said mass of insulating material under initial conditions ofsuillcient temperature of the latter to effect adhesion be-` tween thetwo, said layer of non-conductive inaterial mechanically separating saidinsulating material from said core structure and thereby preventing theformer from adhering to the latter and thereby permitting relativemovement,

l as during bending, between said core structure and said insulating andprotective sheathing structure. and an outer flexible non-metallicsheathing impregnated with moisture-proofing and rire-resistantsaturants and having a sheet .material along its inner face to resistflow of said saturants inwardly from said outer sheathing, and a layerof non-conductive material covering over and bound to said mass ofinsulating material and preventing the latter from adhering to saidsheet material and thereby permitting relative movement. as duringbending,

between said outer sheathing and said insulating and protectivesheathing structure.

20. An insulated conductor construction as claimed in claim 1 in whichsaid helical tape element extends helically about said rcore structureat substantially lthe same pitch as said rib element, there beingbinding means binding said helical tape element to said helicalsheathing means and' to said helical'rib element, whereby said helicaltape element is removed with and as part of the unit` formed by saidhelical sheathing means and said rib element when the latter is Apulled.

21. An insulated conductor construction as claimed in claim 1 in whichsaid helical tape element extends helically about said core structure atsubstantially the same pitch as said rib element, there being interposedbetween said removable covering sheathmeans andsaidhelical'sheathingmeans a tape element that extends helically about said helical sheathingmeans and said helical rib at substantially the pitch of the latter,there being binding means binding both of said helical tape elements tosaid helical sheathing `means and to said helical rib element, wherebyboth of said helical tape elements are removed with and as part ofthe-unit formed by said helical sheathing means and said rib elementwhen the latter is pulled. l

22. In a method' of sheathing and insulating a conductor, the stepswhich comprise jacketing a conductor with insulating means that compriserubber, thereby to form a conductor core strucf ture, winding helicallyabout the latter an impregnable tape element, winding helically thereabout a rib element of substantial thickness and 5 of a non-metallicimpregnable material resistant to compression and at a long lay toprovide a helical space between adjacent turns and at suflicient tensionso that the turns thereof resist displacement, drawing the resultantstructure in 10 an axial direction and during its movement causing saidhelical rib element to pick up and' move with it a plastic material thatis capable of im pregnating the materials or said tape element and ofsaid rib element and that is pliant at con- 15 ductcr-operatingtemperatures, drawing the structure through a device having a restrictedthroat to compact the plastic material into the helical-space and pressit against said tape element and said rib element to impregnate them 20and to become bound thereto, and applying thereover flexiblenon-metallic sheathing means to confine said plastic pliant material insaid helical Space.

23. In a method of sheathing and insulating a conductor, the steps whichcomprise jacketing a conductor with insulating means that compriserubber, applying thereto a wax-like temperatureresponsive coating,applying thereover an impregnable sheet-like material, winding helicallythereabout a rib element of substantial thickness and at a long lay toprovide a helical space between adjacent turns, cornpacting into saidhelical space and in heated condition a mass of insulating material thatis pliant and non-iiowable at operating or installation ranges oftemperature and that is relatively ilowable when in heated condition tothereby cause said heated insulating material to impregnato said sheetmaterial from theouter face of the latter and to become bound theretoand by its heat to aiiect said wax-like temperature-responsive coatingmaterial to impregnate said sheet material from the other face thereof,vand applying thereover exible nonmetallic sheathing means to confinesaid pliant insulating material in said helical space.

CHARLES W. ABBOTT.

